THE SPECTROIL GETS A NEW HEART AND BRAIN

IntroductionWear debris analysis is an important part of any oil analysis program. The Spectroil

RDE spectrometer measures trace quantities of elements dissolved or suspended as

fine particles in lubricants using the time-tested technology of rotating disc electrode

(RDE) atomic emission spectroscopy. The Spectroil RDE spectrometer comes in two

configurations. The Spectroil M is a compact, rugged, and transportable system primarily

for military applications as specified by the DoD JOAP program (Figure 1). The Spectroil

Q100 is a benchtop instrument with a small footprint and is used in commercial

applications (Figure 2). Both Spectroil models are easy to use and provide quick, reliable

analysis of wear metals, contaminants, and additives in lubricants. The standard

commercial calibration program fulfills the requirements of ASTM D6595 Standard Method

for Determination of Wear Metals and Contaminants in Used Lubricating Oils or Hydraulic

Fluids by Rotating Disc Electrode Atomic Emission Spectrometry and is the default option

for commercial customers.1 Other available calibration methods include fuel analysis via

ASTM D6728, coolant analysis, and washdown water analysis.2

THE SPECTROIL GETS A NEW HEART AND BRAIN Randi Price | Spectro Scientific

APPLICATION NOTE

Synopsis

An effective spectrometric oil analysis program is dependent upon interpretation of the analytical data on wear metals, contaminants and additives as measured by a spectrometer. The Spectroil RDE spectrometer is the world’s most recognized system for wear debris analysis of lubricating oils. The Spectroil has been an important part of the US Department of Defense Joint Oil Analysis Program (JOAP) for many years and remains the only approved instrument for that program. Recent enhancements in software and hardware have improved the Spectroil product line, further extending its leadership position as the go-to tool for in-service oil analysis. This paper summarizes the new advances in the Spectroil product line.

Figure 1. Spectroil M

3σ)test results for the commercial program with the new optics

and software algorithm (Table 2). Other calibration programs will

have different LODs due to the difference in the matrix tested. For

example, LODs for the Fuel-Light program with the LD option are

typically much lower than the commercial program (Table 3) and

meet the GE Specification for Liquid Fuel Requirements for GE Aero

Derivative Gas Turbines.

The Spectroil series has always been a leading tool for lubricant

condition monitoring. Recent innovations in the optics and software

algorithms have enabled improvements in the performance and

reliability of the instrument. The rest of this application note

summarizes the new heart (optics) and the new brain (improved

software) of the instrument. The optics manufacturing has been

brought in-house for total control over the capabilities of the

instrument, and the signal processing has been overhauled for

improved analytical performance in varied conditions.

Redesigned Optics The optics of any optical emission spectrometer are the heart of the

system and greatly influence the limits of detection, reproducibility,

and repeatability. Spectro Scientific, an ISO 9001:2008 company,

now manufactures all the Spectroil optics in-house for total control

of the product and its capabilities. This improves product quality

and core performance of the instrument.

Typical performance of the new Spectroil optics calibrated with

the commercial CS-24 program is shown in Tables 1 and 2. The

repeatability at 10 ppm far exceeds the specification of ASTM

D6595, with most elements demonstrating 2X-6X better repeatability

than the reported ASTM D6595 value (Table 1). For example, the

repeatability specification for iron at 10 ppm in ASTM D6595 is 1.7

ppm, while a typical repeatability achieved on the Spectroil is 0.4

ppm. This improvement in repeatability is due to the design of the

optics, the consistent manufacturing of the optics, and the software

used to interpret the results.

An additional benefit of the improved manufacturing, design, and

software is seen in the limits of detection (LODs) (10 burns of 0 ppm,

The Spectroil Gets a New Heart and Brain | 2

Table 1. Repeatability (typical) of 10 ppm listed by element.

Table 2. Typical LODs (ppm, 3σ) listed by element for the

commercial program.

ELEMENTREPEATABILITY

AT 10 PPM(PPM)

Ni

0.3

Cr

Cu

V

Ti

K

0.4

Fe

Mo

Mn

Al

Ca

Na

Mg

Si0.5

Zn

B0.6

Pb

ELEMENT LOD (PPM)

K 0.03

Ag 0.04

Cu 0.05

Ba 0.06

Ca 0.07

Mg 0.10

Ti 0.12

Cr 0.14

Mn 0.15

B 0.22

Zn 0.25

Fe 0.40

Al 0.46

V 0.50

Ni 0.54

Si 0.57

Mo 0.78

Pb 1.64

Sn 2.01

P 4.28

Table 3. Selected LODs for Fuel-Light program with the LD option.

ELEMENT LOD (PPM)

V <0.2

Na+K+Li <0.2

Pb <1.0

Ca <2.0

P <2.0

Figure 2. Spectroil Q100

To demonstrate the power of the new peak searching capability

of the Spectroil, a sample was analyzed on the Spectroil under

different operating conditions without performing an instrument

profile (Figure 4). In Case A, a change in operating temperature

(Condition 1 to Condition 2, difference of 4°C) caused the peak

to shift about 2 pixels. The resulting intensity reported for this

analytical line (without a new profile measurement) changed from

510,000 counts to 160,000 counts with the change in temperature.

If the user didn’t realize the operating conditions changed and

didn’t perform an instrument profile to correct for this change, the

resulting error could be up to 70%. In Case B, the peak searching

algorithm has been implemented and the Spectroil is smart enough

to search for the correct peak position before reporting the result.

The analytical line aligns with the new position of the peak, as if a

new profile measurement had been performed to compensate for the

temperature change, and the accuracy of the measurement is retained.

Redesigned Data ProcessingThe Spectroil has been made “smarter” with a new peak search

algorithm. The results obtained from an instrument are only as

good as its data processing capability. The Spectroil is commonly

operated in non-ideal laboratory environments where fluctuations

in temperature are not uncommon. Variations such as temperature,

humidity, and altitude can introduce minor shifts in the location of

the analytical peaks of each element on the CCD array. This results

in a “drift” of the standardization of the instrument as the peaks

shift away from their expected location (Figure 3). In tightly-

controlled laboratory settings, doing a profile and standardization

check once a day prior to analysis will produce reliable results all

day long. However, in the case of the transportable Spectroil M, a

variable operating environment historically caused instability in the

measured results due to peak drift, forcing some customers to run

multiple profiles per day.

Compensating for instrument drift is an important step to achieving

accurate results. The analytical line is the point in the spectrum

where the intensity of the line is measured and is related to the

concentration of a given element. An instrument profile adjusts the

position of the analytical line, but during a routine measurement the

analytical line is static. If a user neglects to perform an instrument

profile after the environmental conditions have changed, the

accuracy of the results can be affected drastically. To eliminate

this problem, a peak searching algorithm was implemented which

allows the software to automatically locate the peak position during

a measurement, even if it has shifted slightly due to environmental

changes.


Figure 3. Raw Spectroil data for Na line 588.995 at several operating temperatures.

Figure 4. Demonstration of how peak searching compensates for instrument drift. A) Without the peak search algorithm enabled, the analytical line is static and the reported sample concentration may vary up to 70% (intensity = 510,000 counts vs. 160,000 counts) with temperature. B) With the peak search algorithm, the detected signal intensity is much more stable regard-less of the operating condition of the instrument.

35°C 45°C 40°C

Conclusion The Spectroil M and Q100 have been improved due to changes in

the manufacturing and data processing methods. Bringing the

manufacturing of the heart of the system, the optics, in house allows

Spectro Scientific to improve the quality and flexibility of the

platform for future innovations and developments in RDE technology.

The new peak searching capability in the signal processing has made

the instrument smarter and more adaptable to changing operating

conditions without any action required from the user.

References 1 ASTM D6595 Standard Method for Determination of Wear Metals

and Contaminants in Used Lubricating Oils or Hydraulic Fluids by

Rotating Disc Electrode Atomic Emission Spectrometry.

2. ASTM D6728 Standard Test Method for Determination of

Contaminants in Gas Turbine and Diesel Engine Fuel by Rotating

Disc Electrode Atomic Emission Spectrometry.

3. Liquid Fuel Requirements for GE Aero Derivative Gas Turbines.

GE Aviation GE Energy, MID-TD-0000-2, February 2010, Pages 1-7

The benefit of the new peak searching algorithm is clearly seen in

Figure 5. Measurement of a 10 ppm CS-24 standard was performed

at different optic temperatures, from 35°C to 45°C, with burns

performed every 1°C. Without the peak searching capability,

a difference of even a couple of degrees severely impaired the

accuracy of the result for the 10 ppm standard. With the new peak

searching algorithm enabled, the results throughout the entire

temperature range are significantly more stable. Temperature is the

most common variable in the operating environment and was used

to examine the peak drift due to operating conditions but a similar

effect could be seen with other changes in the ambient conditions

such as humidity or altitude. It is clear that the peak searching

capability is a powerful tool to help the user obtain the most

reliable results.


Spectro Scientific | One Executive Drive, Suite 101, Chelmsford, MA 01824-2563 | 978-431-1120 [email protected] | [email protected] An ISO 9001:2008 companyCopyright © 2014 Spectro Scientific All rights reserved. While every effort is made to assure the information in this document is accurate, Spectro does not accept liability for any errors or mistakes that may arise. Specifications are subject to change without notice. Q100Series_AN_2014-10-15

Increase Temperature

Before Peak Searching

Increase Temperature

After Peak Searching

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THE SPECTROIL GETS A NEW HEART AND BRAIN